Electrochemical processing cell

ABSTRACT

Embodiments of the invention may generally provide a small volume electrochemical plating cell. The plating cell generally includes a fluid basin configured to contain a plating solution therein, the fluid basin having a substantially horizontal weir. The cell further includes an anode positioned in a lower portion of the fluid basin, the anode having a plurality of parallel channels formed therethrough, and a base member configured to receive the anode, the base member having a plurality of groves formed into an anode receiving surface, each of the plurality of grooves terminating into an annular drain channel. A membrane support assembly configured to position a membrane immediately above the anode in a substantially planar orientation with respect to the anode surface is provided, the membrane support assembly having a plurality of channels and bores formed therein.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of co-pending U.S. patent applicationSer. No. 10/268,284, filed Oct. 9, 2002, which claims benefit of U.S.provisional patent application Ser. No. 60/398,345, filed Jul. 24, 2002.Each of the aforementioned related patent applications is hereinincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

Embodiments of the present invention generally relate to a low volumeelectrochemical processing cell and methods for electrochemicallydepositing a conductive material on a substrate.

2. Description of the Related Art

Metallization of sub-quarter micron sized features is a foundationaltechnology for present and future generations of integrated circuitmanufacturing processes. More particularly, in devices such as ultralarge scale integration-type devices, i.e., devices having integratedcircuits with more than a million logic gates, the multilevelinterconnects that lie at the heart of these devices are generallyformed by filling high aspect ratio, i.e., greater than about 4:1,interconnect features with a conductive material, such as copper oraluminum. Conventionally, deposition techniques such as chemical vapordeposition (CVD) and physical vapor deposition (PVD) have been used tofill these interconnect features. However, as the interconnect sizesdecrease and aspect ratios increase, void-free interconnect feature fillvia conventional metallization techniques becomes increasinglydifficult. Therefore, plating techniques, i.e., electrochemical plating(ECP) and electroless plating, have emerged as promising processes forvoid free filling of sub-quarter micron sized high aspect ratiointerconnect features in integrated circuit manufacturing processes.

In an ECP process, for example, sub-quarter micron sized high aspectratio features formed into the surface of a substrate (or a layerdeposited thereon) may be efficiently filled with a conductive material,such as copper. ECP plating processes are generally two stage processes,wherein a seed layer is first formed over the surface features of thesubstrate, and then the surface features of the substrate are exposed toan electrolyte solution, while an electrical bias is applied between theseed layer and a copper anode positioned within the electrolytesolution. The electrolyte solution generally contains ions to be platedonto the surface of the substrate, and therefore, the application of theelectrical bias causes these ions to be urged out of the electrolytesolution and to be plated onto the biased seed layer.

Conventional chemical plating cells generally utilize a horizontallypositioned plating cell and a pivot-type substrate immersion process.However, pivotal immersion processes are known to generate bubbles onthe substrate surface as a result of the varying immersion anglegenerated by the pivotal immersion apparatuses. These bubbles are knownto cause plating uniformity problems, and therefore, minimization ofbubbles is desirable. Further, during the pivotal immersion process ofconventional plating cells the substrate surface is not parallel to theanode of the plating cell, and therefore, the electric field across thesurface of the substrate is not constant, which also causes uniformityproblems.

Therefore, there is a need for an improved electrochemical plating cellconfigured to provide for an immersion process that includes maintainingthe substrate at a constant immersion angle during both the immersionand plating processes.

SUMMARY OF THE INVENTION

Embodiments of the invention may generally provide a small volumeelectrochemical plating cell. The plating cell generally includes afluid basin configured to contain a plating solution therein, the fluidbasin having a substantially horizontal upper weir. The cell furtherincludes an anode positioned in a lower portion of the fluid basin, theanode having a plurality of parallel channels formed therethrough, and abase member configured to receive the anode, the base member having aplurality of groves formed into an anode receiving surface, each of theplurality of grooves terminating into an annular drain channel. Amembrane support assembly configured to position a membrane immediatelyabove the anode in a substantially planar orientation with respect tothe anode surface is provided, the membrane support assembly having aplurality of channels and bores formed therein.

Embodiments of the invention may further provide a membrane supportassembly having bores formed partially therethrough from an uppersurface and a plurality of channels formed partially therethrough from alower substrate support surface. The membrane support assembly beingconfigured to support a membrane immediately above an anode in asubstantially planar orientation, while the membrane also is allowed toslightly deform into the channels so that bubbles and other light fluidsmay be urged to the perimeter of the membrane and drained from the anodechamber.

Embodiments of the invention may further provide a base member for ananode assembly. The base member generally includes a recessed portionconfigured to receive the anode. The walls of the recessed portioninclude a plurality of fluid passage channels formed therein. Further,the base of the recessed portion includes an annular drain channel and aplurality of channels extending across the base and terminating at bothends into the drain channel.

Embodiments of the invention further provide an apparatus forelectrochemically plating a metal on a substrate. The apparatusgenerally includes a fluid basin configured to contain a platingsolution, the fluid basin having a substantially horizontal upper weir,a membrane positioned across an inner circumference of the fluid basin,the membrane being configured to separate a cathode chamber positionedin an upper portion of the fluid basin from an anode chamber positionedin a lower portion of the fluid basin, a first fluid inlet configured tosupply a catholyte solution to the cathode chamber and a second fluidinlet configured to supply an anolyte solution to the anode chamber, thecatholyte and anolyte being different solutions, and an anode positionedin the anode chamber, the anode having a substantially planar uppersurface that is positioned at an angle with respect to substantiallyplanar upper weir.

Embodiments of the invention further provide a small volumeelectrochemical plating cell. The electrochemical plating cell generallyincludes a fluid basin configured to contain a plating solution, ananode positioned in the fluid basin, a membrane positioned above theanode across the fluid basin, and a diffusion plate positioned acrossthe fluid basin above the membrane, the diffusion plate and anode beingpositioned in parallel orientation to each other and at a tilt anglewith respect to an upper surface of the plating solution.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the presentinvention can be understood in detail, a more particular description ofthe invention, briefly summarized above, may be had by reference toembodiments, some of which are illustrated in the appended drawings. Itis to be noted, however, that the appended drawings illustrate onlytypical embodiments of this invention and are therefore not to beconsidered limiting of its scope, for the invention may admit to otherequally effective embodiments.

FIG. 1 illustrates a partial sectional perspective view of an exemplaryelectrochemical plating slim cell of the invention.

FIG. 2 illustrates a perspective view of an anode base plate of theinvention.

FIG. 3 illustrates a perspective view of an exemplary anode base plateof the invention having an anode positioned therein.

FIG. 4 illustrates an exploded perspective view of an exemplary membranesupport member of the invention.

FIG. 5 illustrates a partial sectional view of an edge of the platingcell of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The present invention generally provides an electrochemical plating cellconfigured to plate metal onto semiconductor substrates using a smallvolume cell, i.e., a cell weir volume that houses less than about 4liters of electrolyte in the cell itself, preferably between about 1 and3 liters, and potentially between about 2 and about 8 liters ofelectrolyte solution in an adjacent fluidly connected supply tank. Thesesmall volumes of fluid required to operate the cell of the inventionallow the electroplating cell to be used for a predetermined range ofsubstrates, i.e., 100-200, and then the solution may be discarded andreplaced with new solution. The electrochemical plating cell isgenerally configured to fluidly isolate an anode of the plating cellfrom a cathode or plating electrode of the plating cell via a cationmembrane positioned between the substrate being plated and the anode ofthe plating cell. Additionally, the plating cell of the invention isgenerally configured to provide a first fluid solution to an anodecompartment, i.e., the volume between the upper surface of the anode 105and the lower surface of the membrane 502, and a second fluid solution(a plating solution) to the cathode compartment, i.e., the volume offluid positioned above the upper membrane surface. The anode 105 of theplating cell generally includes a plurality of slots formed therein, theplurality of slots being positioned parallel to each other and areconfigured to remove a concentrated hydrodynamic Newtonian fluid layerfrom the anode surface during plating processes. A membrane supportassembly 106 having a plurality of slots or channels formed in a firstside of the assembly, along with a plurality of bores formed into asecond side of the membrane support assembly, wherein the plurality ofbores are in fluid communication with the slots on the opposing side ofthe membrane support assembly.

FIG. 1 illustrates a perspective and partial sectional view of anexemplary electrochemical plating cell 100 of the invention. Platingcell 100 generally includes an outer basin 101 and an inner basin 102positioned within outer basin 101. Inner basin 102 is generallyconfigured to contain a plating solution that is used to plate a metal,e.g., copper, onto a substrate during an electrochemical platingprocess. During the plating process, the plating solution is generallycontinuously supplied to inner basin 102 (at about 1 gallon per minutefor a 3-4 liter plating cell, for example), and therefore, the platingsolution continually overflows the uppermost point of inner basin 102and runs into outer basin 101. The overflow plating solution is thencollected by outer basin 101 and drained therefrom for recirculationinto basin 102. As illustrated in FIG. 1, plating cell 100 is generallypositioned at a tilt angle, i.e., the frame portion 103 of plating cell100 is generally elevated on one side such that the components ofplating cell 100 are tilted between about 3° and about 30°. Therefore,in order to contain an adequate depth of plating solution within innerbasin 102 during plating operations, the uppermost portion of basin 102may be extended upward on one side of plating cell 100, such that theuppermost point of inner basin 102 is generally horizontal and allowsfor contiguous overflow of the plating solution supplied thereto aroundthe perimeter of basin 102.

The frame member 103 of plating cell 100 generally includes an annularbase member 104 secured to frame member 103. Since frame member 103 iselevated on one side, the upper surface of base member 104 is generallytilted from horizontal at an angle that corresponds to the angle offrame member 103 relative to a horizontal position. Base member 104includes an annular or disk shaped recess formed therein, the annularrecess being configured to receive a disk shaped anode 105. Base member104 further includes a plurality of fluid inlets/drains 109 positionedon a lower surface thereof. Each of the fluid inlets/drains 109 aregenerally configured to individually supply or drain a fluid to or fromeither the anode compartment or the cathode compartment of plating cell100. Anode 105 generally includes a plurality of slots 107 formedtherethrough, wherein the slots 107 are generally positioned in parallelorientation with each other across the surface of the anode 105, asillustrated in FIG. 3. The parallel orientation of the slots along withthe tilt angle allows for dense fluids generated at the anode surface toflow downwardly across the anode surface and into one of the slots 107.Plating cell 100 further includes a membrane support assembly 106.Membrane support assembly 106 is generally secured at an outer peripherythereof to base member 104, and includes an interior region 108configured to allow fluids to pass therethrough via a sequence ofoppositely positioned slots and bores. The membrane support assembly 106may include an o-ring type seal positioned near a perimeter of themembrane support assembly 106, wherein the seal is configured to preventfluids from traveling from one side of the membrane 502 secured on themembrane support 106 to the other side of the membrane 502.

FIG. 2 illustrates a perspective view of base member 104. The uppersurface of base member 104 generally includes an recess region 201configured to receive a disk shaped anode 105 in the recessed portion.Further, the surface of recess region 201 generally includes a pluralityof channels 202 formed therein. Each of channels 202 are generallypositioned in parallel orientation with each other and terminate at theperiphery of recess region 201. Additionally, the periphery of recessedregion 201 also includes an annular drain channel 203 that extendsaround the perimeter of recessed region 201. Each of the plurality ofparallel positioned channels 202 terminate at opposing ends into annulardrain channel 203. Therefore, channels 202 may receive dense fluids fromslots 302, as illustrated in FIG. 3, and transmit the dense fluids to adrain channel 203 via base channels 202. The vertical wall that definesrecessed region 201 generally includes a plurality of slots 204 formedinto the wall. The slots 204 are generally positioned in parallelorientation with each other, and further, are generally positioned inparallel orientation with the plurality of channels 202 formed into thelower surface of recessed region 201. Base member 104 also includes atleast one fluid supply conduit 205 configured to dispense a fluid intothe anode region of plating cell 100, along with at least one platingsolution supply conduit 206 that is configured to dispense a platingsolution into the cathode compartment of plating cell 100. Therespective supply conduits 205 and 206 are generally in fluidcommunication with at least one fluid inlets/drains 109 positioned on alower surface of base member 104, as illustrated in FIG. 1. Base member104 generally includes a plurality of conduits formed therethrough (notshown), wherein the conduits are configured to direct fluids received byindividual fluid inlets/drains 109 to the respective cathode and anodechambers of plating cell 100 via conduits 205, 206.

FIG. 3 illustrates a perspective view of base member 104 having the diskshaped anode 105 positioned therein. Anode 105, which is generally adisk shaped copper member, i.e., a soluble-type copper anode generallyused to support copper electrochemical plating operations, generallyincludes a plurality of slots 302 formed therein. The slots 302generally extend through the interior of anode 105 and are in fluidcommunication with both the upper surface and lower surface of anode105. As such, slots 302 allow fluids to travel through the interior ofanode 105 from the upper surface to the lower surface. Slots 302 arepositioned in parallel orientation with each other. However, when anode105 is positioned within recess region 201 of base member 104, theparallel slots 302 of anode 105 are generally positioned orthogonal toboth slots 204 and channels 202 of base member 104, as illustrated inFIG. 3. Additionally, slots 302 generally do not continuously extendacross the upper surface of anode 105. Rather, slots 302 are broken intoa longer segment 303 and a shorter segment 304, with a space 305 betweenthe two segments, which operates to generate a longer current paththrough anode 105 from one side to the other. Further, adjacentlypositioned slots 302 have the space 305 positioned on opposite sides ofthe anode upper surface. The current path from the lower side of anodeto the upper side of anode generally includes a back and forth type pathbetween the respective slots 302 through the spaces 305. Further, thepositioning of spaces 305 and slots 302 provides for improvedconcentrated Newtonian fluid removal from the surface of the anode 105,as the positioning of slots 302 provides a shortest possible distance oftravel for the dense fluids to be received in slots 302.

FIG. 4 illustrates an exploded perspective view of an exemplary membranesupport assembly 106 of the invention. Membrane support assembly 106generally includes an upper ring shaped support member 401, anintermediate membrane support member 400, and a lower support member402. Upper and lower support member's 401 and 402 are generallyconfigured to provide structural support to intermediate membranesupport member 400, i.e., upper support member 401 operates to secureintermediate membrane support member 400 to lower support member 402,while lower support member 402 receives intermediate membrane supportmember 400. Intermediate membrane support member 400 generally includesa substantially planar upper surface having a plurality of borespartially formed therethrough. A lower surface of intermediate membranesupport member 400 generally includes a tapered outer portion 403 and asubstantially planar inner membrane engaging surface 406. An uppersurface of lower support member 402 may include a corresponding taperedportion configured to receive the tapered section 403 of intermediatemembrane support member 400 thereon. The membrane engaging surface 406generally includes a plurality of parallel positioned/orientatedchannels 405. Each of the channels 405 formed into the lower surface ofintermediate membrane support member 400 are in fluid communication withat least one of the plurality of bores (not shown) partially formedthrough the planar upper surface. The channels 405 operate to allow amembrane (shown in FIG. 5) positioned in the membrane support assembly400 to deform slightly upward in the region of the channels 405, whichprovides a flow path for air bubbles and less dense fluids in thecathode chamber to travel to the perimeter of the membrane and beevacuated from the anode chamber.

In operation, the plating cell 100 of the invention provides a smallvolume (electrolyte volume) processing cell that may be used for copperelectrochemical plating processes, for example. Plating cell 100 may behorizontally positioned or positioned in a tilted orientation, i.e.,where one side of the cell is elevated vertically higher than theopposing side of the cell, as illustrated in FIG. 1. If plating cell 101is implemented in a tilted configuration, then a tilted head assemblyand substrate support member may be utilized to immerse the substrate ata constant immersion angle, i.e., immerse the substrate such that theangle between the substrate and the upper surface of the electrolytedoes not change during the immersion process. Further, the immersionprocess may include a varying immersion velocity, i.e., an increasingvelocity as the substrate becomes immersed in the electrolyte solution.The combination of the constant immersion angle and the varyingimmersion velocity operates to eliminate air bubbles on the substratesurface.

Assuming a tilted implementation is utilized, a substrate is firstimmersed into a plating solution contained within inner basin 102. Oncethe substrate is immersed in the plating solution, which generallycontains copper sulfate, chlorine, and one or more of a plurality oforganic plating additives (levelers, suppressors, accelerators, etc.)configured to control plating parameters, an electrical plating bias isapplied between a seed layer on the substrate and the anode 105positioned in a lower portion of plating cell 100. The electricalplating bias generally operates to cause metal ions in the platingsolution to deposit on the cathodic substrate surface. The platingsolution supplied to inner basin 102 is continually circulated throughinner basin 102 via fluid inlets/drains 109 More particularly, theplating solution may be introduced into plating cell 100 via a fluidinlets/drains 109. The solution may travel across the lower surface ofbase member 104 and upward through one of plating solution supplyconduits 206. The plating solution may then be introduced into thecathode chamber via a channel formed into plating cell 100 thatcommunicates with the cathode chamber at a point above membrane support106, as illustrated and described with respect to FIG. 5. Similarly, theplating solution may be removed from the cathode chamber via a fluiddrain positioned above membrane support 106, where the fluid drain is influid communication with one of fluid inlets/drains 109 positioned onthe lower surface of base member 104 via one of plating solution supplyconduits 206. For example, base member 104 may include first and secondplating solution supply conduits 206 positioned on opposite sides ofbase member 104. The oppositely positioned plating solution supplyconduits 206 may operate to individually introduce and drain the platingsolution from the cathode chamber in a predetermined direction, whichalso allows for flow direction control. The flow control directionprovides control over removal of light fluids at the lower membranesurface, removal of bubbles from the anode chamber, and assists in theremoval of dense or heavy fluids from the anode surface via the channels202 formed into base 104.

Once the plating solution is introduced into the cathode chamber, theplating solution travels upward through diffusion plate 110. Diffusionplate 110, which is generally a ceramic or other porous disk shapedmember, generally operates as a fluid flow restrictor to even out theflow pattern across the surface of the substrate. Further, the diffusionplate 110 operates to resistively damp electrical variations in theelectrochemically active area between the anode and the cation membranesurface, which is known to reduce plating uniformities. Additionally,embodiments of the invention contemplate that the ceramic diffusionplate 110 may be replaced by a hydrophilic plastic member, i.e., atreated PE member, an PVDF member, a PP member, or other material thatis known to be porous and provide the electrically resistive dampingcharacteristics provided by ceramics. However, the plating solutionintroduced into the cathode chamber, which is generally a platingcatholyte solution, i.e., a plating solution with additives, is notpermitted to travel downward through the membrane 502 positioned on thelower surface 404 of membrane support assembly 106 into the anodechamber, as the anode chamber is fluidly isolated from the cathodechamber by the membrane. The anode chamber includes separate individualfluid supply and drain sources configured to supply an anolyte solutionto the anode chamber. The solution supplied to the anode chamber, whichmay generally be copper sulfate in a copper electrochemical platingsystem, circulates exclusively through the anode chamber and does notdiffuse or otherwise travel into the cathode chamber, as the membranepositioned on membrane support assembly 106 is not fluid permeable ineither direction.

Additionally, the flow of the fluid solution (anolyte, i.e., a platingsolution without additives, which may be referred to as a virginsolution) into the anode chamber is directionally controlled in order tomaximize plating parameters. For example, anolyte may be communicated tothe anode chamber via an individual fluid inlets/drains 109. Fluidinlets/drains 109 is in fluid communication with a fluid channel formedinto a lower portion of base member 104 and the fluid channelcommunicates the anolyte to one of fluid supply conduits 205. A sealpositioned radially outward of fluid supply conduits 205, in conjunctionwith the surrounding structure, directs the anolyte flowing out of fluidsupply conduits 205 upward and into slots 204. Thereafter, the anolytegenerally travels across the upper surface of the anode 105 towards theopposing side of base member 104, which in a tilted configuration, isgenerally the side of plating cell 100. The anolyte travels across thesurface of the anode below the membrane positioned immediately above.Once the anolyte reaches the opposing side of anode 105, it is receivedinto a corresponding fluid channel 204 and drained from plating cell 100for recirculation thereafter.

During plating operations, the application of the electrical platingbias between the anode and the cathode generally causes a breakdown ofthe anolyte solution contained within the anode chamber. Moreparticularly, the application of the plating bias operates to generatemultiple hydrodynamic or Newtonian layers of the copper sulfate solutionwithin the anode chamber. The hydrodynamic layers generally include alayer of concentrated copper sulfate positioned proximate the anode, anintermediate layer of normal copper sulfate, and a top layer of lighterand depleted copper sulfate proximate the membrane. The depleted layeris generally a less dense and lighter layer of copper sulfate than thecopper sulfate originally supplied to the anode compartment, while theconcentrated layer is generally a heavier and denser layer of coppersulfate having a very viscous consistency. The dense consistency of theconcentrated layer proximate the anode causes electrical conductivityproblems (known as anode passivation) in anodes formed without slots302. However, slots 302, in conjunction with the tilted orientation ofplating cell 100, operate to receive the concentrated viscous layer ofcopper sulfate and remove the layer from the surface of the anode, whicheliminates conductivity variances. Further, plating cell 100 generallyincludes one side that is tilted upward or vertically positioned abovethe other side, and therefore, the surface of anode 105 is generally aplane that is also tilted. The tilt causes the layer of concentratedcopper sulfate generated at the surface of the anode to generally flowdownhill as a result of the gravitational force acting thereon. As theconcentrated copper sulfate layer flows downhill, it is received withinone of slots 302 and removed from the surface of the anode 105. Asdiscussed above, slots 302 are generally parallel to each other and areorthogonal to the slots 204. Therefore, slots 302 are also orthogonal tochannels 202 and formed into the lower surface of base member 104. Assuch, each of slots 302 finally intersects several of channels 202. Thisconfiguration allows the concentrated copper sulfate received withinslots 302 to be communicated to one or more of channels 202. Thereafter,the concentrated copper sulfate may be communicated via channels 202 tothe annular drain channel 203 positioned within recess 201. The drainchannel 203 in communication with channels 202 may generally becommunicated through base plate 104 and back to a central anolyte supplytank, where the concentrated copper sulfate removed from the anodesurface may be recombined with a volume of stored copper sulfate usedfor the anolyte solution.

Similarly, the upper portion of anode chamber generates a diluted layerof copper sulfate proximate the membrane. The diluted layer of coppersulfate may be removed from the anode chamber via an air vent/drain 501,as illustrated in FIG. 5. Air vent/drain 501, which may include multipleports, is generally positioned on the upper side of electrochemicalplating cell 100, and therefore, is positioned to receive both bubblestrapped within anode chamber, as well as the diluted copper sulfategenerated at the membrane surface. Air vent/drain 501 are generally influid communication with the anolyte tank discussed above, andtherefore, communicates the diluted copper sulfate received therein backto the anolyte tank, where the diluted copper sulfate may combine withthe concentrated copper sulfate removed via slots 302 to form thedesired concentration of copper sulfate within the anolyte tank. Anybubbles trapped by air vent/drain 501 may also be removed from thecathode chamber vented to atmosphere or simply maintained within theanolyte tank and not recirculated into the cathode chamber.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof, and the scope thereof isdetermined by the claims that follow

1. An anode used to electrochemically plate a metal on a substrate,comprising a substantially disk-shaped member having a plurality slotsformed therethrough.
 2. The anode of claim 1, wherein substantiallydisk-shaped member is manufactured from a metal that is to be plated inan electrochemical plating process.
 3. The anode of claim 1, whereinsubstantially disk-shaped member is made of copper.
 4. The anode ofclaim 1, wherein the plurality of slots comprise a plurality of longersegments and a plurality of shorter segments, each of the plurality oflonger segments being positioned in longitudinal abutment with acorresponding one of the plurality of shorter segments and separatedtherefrom by a remaining portion of the anode.
 5. An anode used in anelectrochemical plating cell, comprising: a substantially disk-shapedmember having a plurality slots formed therethrough, wherein theplurality of slots are aligned parallel to a first direction.
 6. Theanode of claim 5, wherein substantially disk-shaped member ismanufactured from a metal that is to be plated in an electrochemicalplating process.
 7. The anode of claim 5, wherein substantiallydisk-shaped member is made of copper.
 8. The anode of claim 5, whereinthe plurality of slots comprise one or more slots that have a firstlength and one or more slots that are a second length, wherein the firstlength is longer than the second length.
 9. An anode used in anelectrochemical plating cell, comprising: a substantially disk-shapedmember having a plurality slots formed therethrough, wherein theplurality of slots are aligned parallel to a first direction and theplurality of slots comprise: a first group of slots that includes atleast a first slot that is a first length and has a first end, and asecond slot that is a second length and has a second end, wherein thesecond slot and the first slot are oriented so that they form a firstspace between the first end and the second end; and a second group ofslots that are parallel to the first group of slots and the firstdirection, wherein the second group of slots includes at least a thirdslot that is a third length and has a third end, and a fourth slot thatis a fourth length and has a fourth end, wherein the fourth slot and thethird slot are oriented so that they form a second space between thethird end and the fourth end.
 10. The anode of claim 9, wherein thesecond slot and the first slot are oriented so that they are collinearand the fourth slot and the third slot are oriented so that they arecollinear.
 11. The anode of claim 9, wherein the first and second groupof slots are spaced a distance apart in a direction substantiallyperpendicular to the first direction.
 12. The anode of claim 9, whereinsubstantially disk-shaped member is manufactured from a metal that is tobe plated in an electrochemical plating process.
 13. The anode of claim9, wherein substantially disk-shaped member is made of copper.